1. Field of the Invention
The present invention relates to a method and apparatus for inventory control, specifically to disposable elements and general consumable items that are used in a hospital or medical facility, and more specifically to point-of-care sample analysis systems that use different types of disposable devices.
2. Background Information
For hospitals, the recent introduction of point-of-care testing capabilities has created unique requirements for inventory control. The inventory control requirements arise from the use of multiple types of disposable sample testing devices at various locations within a hospital. The hospital must provide an adequate supply of each type of device at each site of use. However, the hospital tries to be mindful of the cost of carrying excess inventory at each site. This is also true for other locations where point-of-care testing occurs, such as military combat sites, cruise ships and nursing homes.
Certain sample testing devices have a finite shelf-life, in which the shelf-life may depend upon whether the sample testing device is refrigerated or maintained at ambient or room temperature, e.g., room temperature for a hospital. For example, a blood testing device may have a shelf-life of six to nine months when refrigerated, or a limited shelf-life of two weeks at ambient temperature. Because of the differences in shelf-life, a hospital will generally store devices at a central refrigerated location, and deliver devices to specific departments as demand requires. These departments may or may not have available refrigerated storage, which consequently affects the inventory they will maintain. In certain departments, general storage may be limited, which will also affect what level of inventory they maintain.
Point-of-care sample analysis systems are generally based on a re-usable reading apparatus that performs sample tests using a disposable device, e.g., a cartridge or strip, that contains analytical elements, e.g., electrodes or optics for sensing analytes such as, for example, pH, oxygen and glucose. The disposable device can optionally include fluidic elements (e.g., conduits for receiving and delivering the sample to the electrodes or optics), calibrant elements (e.g., aqueous fluids for standardizing the electrodes with a known concentration of the analyte), and dyes with known extinction coefficients for standardizing optics. The reading apparatus contains the electrical circuitry and other components for operating the electrodes or optics, making measurements, and doing computations. The reading apparatus also has the ability to display results and communicate those results to laboratory and hospital information systems (LIS and HIS, respectively), for example, via a computer workstation. Communication between the reading apparatus and a workstation, and between the workstation and a LIS, can be via, for example, an infrared link, a wired connection, wireless communication, or any other form of data communication that is capable of transmitting and receiving electrical information, or any combination thereof.
One benefit of point-of-care sample testing systems is the elimination of the time-consuming need to send a sample to a central laboratory for testing. Point-of-care sample testing systems allow a nurse, at the bedside of a patient, to obtain a reliable, quantitative, analytical result, comparable in quality to that which would be obtained in a laboratory. In operation, the nurse selects a device with the required panel of tests, draws a sample, dispenses it into the device, optionally seals the device with, for example, a snap-closure, and inserts the device into the reading apparatus. While the particular order in which the steps occur may vary between different point-of-care systems and providers, the intent of providing rapid sample test results close to the location of the patient remains. The reading apparatus then performs a test cycle, i.e., all the other analytical steps required to perform the tests. Such simplicity gives the physician quicker insight into a patient's physiological status and, by reducing the time for diagnosis, enables a quicker decision by the physician on the appropriate treatment, thus enhancing the likelihood of a successful patient treatment.
In the emergency room and other acute-care locations within a hospital, the types of sample tests required for individual patients tend to vary. Thus, point-of-care systems generally offer a range of disposable devices with different sample tests, or combinations of sample tests. For example, for blood analysis devices, in addition to traditional blood tests, including oxygen, carbon dioxide, pH, potassium, sodium, chloride, hematocrit, glucose, urea, creatinine and calcium, other tests can include, for example, prothrombin time (PT), activated clotting time (ACT), activated partial thromboplastin time (APTT), troponin, creatine kinase MB (CKMB) and lactate. While devices typically contain between one and ten tests, it will be appreciated by persons of ordinary skill in the art that any number of test may be contained on a device. For example, a device for genetic screening may include numerous tests. To illustrate the need for different devices, a patient suspected of arrhythmia may require a device with a test combination that includes a potassium test, whereas a patient suspected of a diabetic coma may require a device with a test combination that includes a glucose test. An emergency room will need to have sufficient inventory of both types of device to ensure the supply meets the anticipated workload, while seeking to limit the economic cost associated with carrying an unnecessarily high inventory.
A given hospital may use numerous different types of devices and accordingly needs to maintain a combination of some or all of these at each point-of-care testing location within the hospital. These locations can include, for example, an emergency room (ER), a critical care unit (CCU), a pediatric intensive care unit (PICU), an intensive care unit (ICU), a renal dialysis unit (RDU), an operating room (OR), a cardiovascular operating room (CVOR), general wards (GW) and the like. Other hospital locations can be used to deliver point-of-care testing, as can other non-hospital-based locations where medical care is delivered, including, for example, MASH units, nursing homes, and cruise, commercial and military ships, and the like. FIG. 1 depicts an example of monthly device consumption rates at different locations in a hospital versus the different available device types. It will be appreciated by persons of ordinary skill in the art that the demand for particular devices may vary significantly between locations within, for example, a hospital.
Previously, inventory control of devices at the point-of-care relied on direct human intervention. Typically, personnel in the emergency room and/or other locations would call the hospital laboratory, where disposable devices are usually centrally stored to place an order. Alternatively, the hospital laboratory can control the disposable device storage at a central repository. The hospital laboratory would then request additional devices of specific types to be delivered to the requesting department. The central repository would then arrange for the devices to be delivered. Alternatively, a person from the laboratory, e.g., a designated point-of-care testing coordinator, would be responsible for regularly visiting point-of-care testing locations, checking device inventory needs and ensuring that those needs are met. Because of the manual nature of this inventory control scheme, there are several opportunities for delay and possible human error.
Once devices are delivered from the central repository, the devices can be stored at a convenient location, e.g., somewhere close to the patient. The convenient location will vary by department, but can include, for example, at the patient bedside (e.g., when the reading apparatus is part of a patient monitoring system), at a nursing station, in an auxiliary room attached to a ward, in a satellite laboratory attached to a critical care unit, and the like. One skilled in the art will recognize that where devices are stored at the bedside, the devices are unlikely to be refrigerated, whereas devices stored in a satellite laboratory may be refrigerated.
Typically, devices are supplied by the manufacture to the hospital in boxes with a given number of units, e.g., 25 or 50 units, or any number of units. The central repository in the hospital can supply these devices to the different departments in boxes or individually. Thus, the minimum inventory level for a department can be set in terms of the number of available unopened boxes of devices or on an absolute number of available individual devices.
Current inventory control systems and methods for handling point-of-care device inventory place the end-user, usually a nurse, at the center of the process. Essentially, the end user had to log or visually monitor the number of boxes of each type of device at their location and call the central repository to order more, as they see fit. Alternatively, a person from the laboratory was responsible for coordinating point-of-care testing by making regular visits to each site and ensuring devices are delivered when needed.
Thus, in creating the new environment of point-of-care sample testing, where a nurse performs sample tests at or close to the bedside of the patient, many of the previous problems associated with delay due to sample transportation to a hospital laboratory for analysis have been solved. The following patents relating to point-of-care sample testing are assigned to the same assignee as the present application: DISPOSABLE SENSING DEVICE FOR REAL TIME FLUID ANALYSIS, Lauks et al., U.S. Pat. No. 5,096,669; WHOLLY MICROFABRICATED BIOSENSORS AND PROCESS FOR THE MANUFACTURE AND USE THEREOF, Cozzette et al., U.S. Pat. No. 5,200,051; METHOD FOR ANALYTICALLY UTILIZING MICROFABRICATED SENSORS DURING WET-UP, Cozzette et al., U.S. Pat. No. 5,112,455; SYSTEM, METHOD AND COMPUTER IMPLEMENTED PROCESS FOR ASSAYING COAGULATION IN FLUID SAMPLES, Opalsky et al., U.S. Pat. No. 6,438,498; MICROFABRICATED APERTURE-BASED SENSOR, Davis et al., U.S. Pat. No. 6,379,883; APPARATUS FOR ASSAYING VISCOSITY CHANGES IN FLUID SAMPLES AND METHOD OF CONDUCTING SAME, Davis et al., U.S. Pat. No. 5,447,440; REUSABLE TEST UNIT FOR SIMULATING ELECTROCHEMICAL SENSOR SIGNALS FOR QUALITY ASSURANCE OF PORTABLE BLOOD ANALYZER INSTRUMENTS, Zelin et al., U.S. Pat. No. 5,124,661; STATIC-FREE INTERROGATING CONNECTOR FOR ELECTRICAL COMPONENTS, Lauks, U.S. Pat. No. 4,954,087; and REFERENCE ELECTRODE, METHOD OF MAKING AND METHOD OF USING SAME, Lauks, U.S. Pat. No. 4,933,048.
However, new inventory management issues were created as a consequence of the transition to point-of-care sample analysis.